Dinara Safina reached her second Grand Slam semi-final of the year with a 6-2 6-3 win over Flavia Pennetta.
The Russian sixth seed will face now Serena Williams - a 7-6 (8-6) 7-6 (9-7) victor over sister Venus - in the last four of the US Open after a routine success on the Arthur Ashe court.
Safina had never been beyond the quarter-finals of any Grand Slam before reaching the final at the French Open in May, when she was beaten in straight sets by Ana Ivanovic.
Safina, who was also runner-up at the Beijing Olympics, raced through the first set and then fought back from a break down to take the second. “It’s great,” Safina said. “I’m getting closer to reaching the same thing as my brother (Marat Safin, the 2000 champion), so I hope that one day we can have the same titles.”
Pennetta, who beat Amelie Mauresmo to reach her first Grand Slam quarter-final, was overpowered by her opponent in the early stages.
When she broke for a 2-1 lead in the second set she appeared to be back in the contest, but Safina won five of the next six games.
Safina’s reward is a semi-final clash with fourth seed Serena Williams, who edged a tightly-contested match with her sister Venus.
Serena had trailed 5-3 in both sets, facing set points on each occasion, however she broke back to reach the semi-finals for the first time at Flushing Meadows in six years.
And the 26-year-old, who won the US Open title in 1999 and 2002, was thankful for a couple of mistakes from Venus.
“She made a couple of errors. It was really lucky for me because she never makes those errors,” Serena said.
“I can’t say I was disappointed. I obviously want the best for her, but in that situation you want to win, too.”